> theoretically any existing dam could be converted? Just need to pump some water back upstream when there's excess load in the system. For that, you need wate

> theoretically any existing dam could be converted? Just need to pump some water back upstream when there's excess load in the system. For that, you need water that can be pumped back upstream, that is, you need also a lower reservoir. If your dam discharges directly into a river, you won't have enough water downstream of the dam to pump back upstream. Not all dams have suitable geology to form another reservoir below them. An alternative would be to create a new reservoir higher than the dam, using the existing dam as the lower reservoir, with a set of tunnels with the reversible generator/pumps linking both reservoirs (this new upper reservoir does not need to be in the path of the river).